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Thread: Crank Case Ventilation fully explained. (Turbocharged edition.)

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Posts: 191-200 of 201
2015-08-06 02:18:01
#191
Originally Posted by BenFenner
Looks can be deceiving.

Why not modify what you have to point the filter up?

Yes, it can be used as a drain. The stock system uses it as a drain, and it looks like your current setup also uses it as a drain as well.

The main function of the valve is to not vent (out that particular outlet) when intake is under boost? There isnt a PCV valve on the other end of the rocker cover. im not suffering from any boost leaks nor is it going to the intake anymore, hence it seemed pretty useless to me. am I forgetting something?

Filter facing up would hit the bonnet, and I also have to delete my bonnet gas struts for a carbon bonnet so the bonnet stick has to sit where the catch can is now. I also suspect the current catch can has no baffles or steel wool or anything inside.

I wasn't sure if it was a suitable drain because the diagrams in this thread show gas traveling away from the crankcase, so thought I would just ask.


Also just a tip for older SR20 rocker covers... I've tapped the far vent for an M18 to AN -8 oil fitting. Nothing else really fit.

Last edited by Leroy Peterson on 2015-08-06 at 02-21-21.
2015-08-06 11:43:55
#192
Originally Posted by Leroy
The main function of the valve is to not vent (out that particular outlet) when intake is under boost? There isnt a PCV valve on the other end of the rocker cover. im not suffering from any boost leaks nor is it going to the intake anymore, hence it seemed pretty useless to me. am I forgetting something?
Yes, you are missing something. The valve is there to prevent flow in the wrong direction, but the entire pathway is there for different reasons than the other pathway.
Make with the reading: http://www.sr20-forum.com/information-library/34413-crank-case-ventilation-fully-explained-naturally-aspirated-edition.html
2015-08-06 18:01:08
#193
Originally Posted by BenFenner
Yes, you are missing something. The valve is there to prevent flow in the wrong direction, but the entire pathway is there for different reasons than the other pathway.


For the longest time I thought it was for one way valve purpose only, but seems like PCV valves open at different rates depending on the conditions (thus they vent more or less crancase blowby depending on the driving condition). Fred's thread that you linked above goes in great detail to cover this.
2015-08-06 18:19:52
#194
Yes, it is a tuned, variable flow one-way check valve. Fred's thread has good diagrams. It is still a one-way check valve, so I decided to simplify that part of things for my explanation.
2016-04-22 23:10:21
#195
first off i wana say awesome write up...lots of great info



second i wana say kingtal0n is either a troll or a moron or idk but go away ur dumb

and third i would love some input on my situation, I just got a sr and wana have a good running healthy motor thats my main goal. so idc about emmisions thats my lowest priority. my biggest issues are 1) i didnt get the stock "oil can" with my setup, the kid just ran a hose from the block vent 2 the T in the valve cover and then idk where next. So as far as the actual pcv valve side i can just leave that alone for now right, keep the stock pcv valve and run it right there 2 the intake manifold, thats how it was and thats how ill leave it. but for the WOT side, whats my best option?
2016-04-23 00:59:16
#196
im thinking i should run that t fitting into a catch can and then back to the intake? and according 2 the diagram its after the maf? and before the turbo? isnt that going 2 be unmeasured air cuz its after the maf?
2016-04-23 01:07:27
#197
Originally Posted by BenFenner
EPA is happy.
Also mentioned before and extremely important to understand is the fact that the ventilation of the crankcase dumps into the intake tract upstream (after) the MAF sensor. This is to prevent any oily blow-by gasses from quickly contaminating and/or ruining the MAF sensor. I'm not going to get into the pros and cons of moving the MAF sensor to the pressure side of the intake tract right now, but suffice it to say, you need to avoid recirculating blow-by emissions coming into contact with the MAF element. (Cars equipped with a MAP sensor as the primary air metering device can ignore this warning.)


is that what u where getting at there? is it just an insignificant ammount? because the blow off valve is technically unmeasured air also right?
2016-04-23 03:50:31
#198
Originally Posted by Ben
im thinking i should run that t fitting into a catch can and then back to the intake? and according 2 the diagram its after the maf? and before the turbo?
Yes, that's correct and a decent plan.

Originally Posted by Ben
isnt that going 2 be unmeasured air cuz its after the maf?
Well, it's technically metered air because it went through the MAF once already. It's seconds late, but
2016-04-23 04:01:53
#199
Originally Posted by Ben
Originally Posted by BenFenner
EPA is happy.
Also mentioned before and extremely important to understand is the fact that the ventilation of the crankcase dumps into the intake tract upstream (after) the MAF sensor. This is to prevent any oily blow-by gasses from quickly contaminating and/or ruining the MAF sensor. I'm not going to get into the pros and cons of moving the MAF sensor to the pressure side of the intake tract right now, but suffice it to say, you need to avoid recirculating blow-by emissions coming into contact with the MAF element. (Cars equipped with a MAP sensor as the primary air metering device can ignore this warning.)


is that what u where getting at there? is it just an insignificant ammount? because the blow off valve is technically unmeasured air also right?
In that quote, I'm talking about making sure oily blow-by gasses don't travel past the MAF element and foul it up. The amount of oil is significant, and will ruin a MAF's readings quickly, and then ruin the MAF soon after.

As for the BOV being unmetered air... In a properly recirculated system, the BOV discharge is still metered air, since it traveled through the MAF at one point in it's journey. That might have been seconds in the past, but it was metered at one point.
2016-04-23 04:31:13
#200
glad were on the same page!!!, and like i said great write up!!!! and im so happy u still keep up with this post, im sure its helped alot of people!!! anyway thanks again!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!
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